What is it?

The Audi R8 V12 TDi Le Mans is the world's first diesel-powered supercar. At least that's what some are calling it. Audi is smart enough to call its new R8 V12 TDi a super-sports car, pitching it against the likes of the Ferrari F430 rather than full blown supercars of the Bugatti Veyron, Ferrari Enzo and McLaren F1 ilk.

But be in no doubt; this is a proper £100,000-plus exotic – and the first to drink from the dark side of the pump.

It's still a concept car for now, but only until the dust settles, the media monitoring results come in, and Audi's suspicions are confirmed. It's convinced, you see, that the time of the mid-engined, V12, diesel-powered, quattro-driven sports car has come. But for good reason? Read on...

What's it like?

Challenging. Different. Fascinating. And also genuinely quick, if lacking in a few of the other attractions you normally get with exotica like this.

The word is that Audi had several multi-million dollar offers for this concept car at the Detroit motor show, on the strength of its looks alone. That's probably because it's a devilishly purposeful-looking car.

In making it, the stylists substituted most of the standard R8's carbonfibre for aluminium, and added bumper- and sill-extensions in the same polished alloy, as well as a proper underbody air diffuser. The result looks threatening and aggressive, like the kind of car that devours roads, and whatever may be on them, without so much as a change of gear.

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Which is exactly as it should be, since this particular R8 has the wherewithal to do exactly that. Powered by a Hungarian-built twin-turbodiesel V12 (the same, but for a dry sump, that you'll find in the new Q7 V12), this car will do 62mph in 4.2sec, 100mph in less than 10sec, and more than 190mph flat out.

More phenomenal than that is its in-gear pulling power, which is the truest measure of everyday performance on the road. 738lb ft is almost as much twist as a BMW M6 and a Ferrari F430 muster between them. In a car that should weigh just 150kg more than a V8-powered R8 in road-going guise, or about 1750kg. Doesn't take a genius to work out why Audi has been so excited about performance diesels, does it?

This car will also do an average 25mpg, of course, and emits about 250g/km of CO2 – which are figures usually associated with hot hatches, and never before with near-200mph supercars.

So does it feel as savagely fast as the figures suggest? Well, on the back of this test drive it's difficult to be definitive. Audi's test route was short, and its concern for the one working prototype of this car considerable. We weren't allowed to do more than 35mph, proper cornering was forbidden, and full bore starts were out too.

That effectively reduced us to a couple of runs around what amounted to little more than car park access roads. So I can report that this R8 appears to steer and ride much like a standard one (ie very nicely indeed). It's got Audi's excellent magnaride adjustable dampers, which add a couple of new dimensions to its ride and handling repertoire.

And yes, its certainly quick – quicker even than anybody really knows yet. I risked a knuckle-rapping by giving the car full throttle in 3rd, from 25mph and 1000rpm; it mugged the tarmac and began hurtling at the horizon with an urgency that made me painfully aware of the driver’s seat’s lumbar support. There was no wheelspin, no turbo lag. I only felt the full savagery for a couple of seconds, but that was enough to convince me that this car deserves a future in production.

And here comes the really mad part; apparently, that was literally just half the story. Audi had to fit an A4 gearbox into this car, as it doesn't currently have one small enough to fit, but man enough to handle 1000 newton meters. As a result, the car's V12 is only running at half-wick; 369lb ft. Believe me, then, when I state that the road car will be quicker than, and yet almost wholly unlike, any sports car you've ever driven.

Should I buy one?

Well, you'll probably have to wait until 2010. That's as soon as Audi is likely to be able to put the R8 TDi into production, probably with a new transverse 7-speed DSG gearbox.

And you'll have to have quite a particular taste in fast cars. You'll have to like them as frugal and low-CO2 as possible; interesting to listen to, but not at all sonorous; riveting to drive, without being quite as involving as a high-revving petrol; and you'll have to be into massive real world performance delivered in an easily-accessed, totally undramatic way.

If you run a Porsche 911 GT3 then, you'll probably hate this car, and would be well advised to steer clear. But if you drive an AMG Merc, on the other hand – and there are plenty of those on the road these days – this R8 could be right up your alley, heater plugs and all.

Join the debate

David88, I never thought I'd buy a diesel 3yrs ago, thought they were a French quirk!! Now I've a 335d coupe and can't honestly say I don't miss a petrol too much, apart from that raspy sound and the diesel still clatters for 5-10mins on starting from cold.

When you floor it though you get a nice grunt and of course that huge wallop of torque that may not be quite as exciting as a petrols bhp but on a motorway the torque trounces the power - and doubles the fuel consumption. If you do lots of motorway miles diesels the way to go. If you do A and B roads, stay with the fun of petrol.

This Audi's 4.2sec 0-62mph, under 10secs to 100mph and more than 190mph flat out is pretty quick. But the in-gear power for everyday performance with 738lbs of torque (my 335 has 428lb and it just crushes you forward like granite in a velvet glove) must be simply phenominal to experience in something about the same weight as my coupe.

The MPG figures are a tad disappointing though. Would I buy one. I'd have to try it out. If you want a sportcar petrol is still the way to go but as most of us have never driven and experienced something like this (it is quite radical of Audi, well done) it would be churlish not to try this diesel sportscar before you buy. And try this twin turbocharged Panzer' on a motorway and that tidal wave of torque could wash all your doubts away.

I too am driving my first diesel car. Had 6 petrol cars previously. Never wanted a diesel but financial reasons dictated it. Went from a 1.8T petrol to a 2.0TDi. Similer levels of bhp but the torque of the diesel is amazing! So much more useable than top-end horse power. Diesel power requires adapting your driving style though due to much narrower power band. But ive totally changed my views. Besides I have a motorbike for proper high revving petrol fun. ;-)

I don't see the big fuss about performance diesels.
Compare 335i to 335d for instance. Both turbos, so that levels the playing field.
The diesel emits 12% less CO2, but makes 9% less power.
In power/C02 terms, the diesel is 5% better. Is that what all the fuss is about?
This gap widens if you use mpg rather than CO2, but this is just because diesel is more energy dense.
In favour of diesel: power at lower revs for "effortless" speed, 5% more efficient.
In favour of petrol: wider rev range, better noise, lighter engines, wider range of gearboxes, no filthy particulates, no oily hands at the pump.
In technology terms the only thing that Audi has proven is that forced induction is an efficient way of producing more power when you need it. Which was bleeding obvious already.

John - I considered both 335i and 335d before I purchased. What swayed it for me was for both motorway and urban driving the diesel wins pretty convincingly.

I've 'boogied' with two 535d in my Turbo S (444lb torque and 444bhp) in Europe and whilst both 535d's began to disappear in the rear view mirror (eventually) both stuck to me so close I couldn't work how (535i's get blown away like every other car in a matter of seconds with the Turbo). It was the 428lb torque that kept them close.

Then you add the MPG factor (Turbo 12mpg - 335i 20-30mpg - 335d 30-40mpg). I also had a 330i until I chopped it in for the 335d last year. Best car, and all-rounder, I ever owned but still drunk quite a bit in urban and motorway driving.

If I was to buy a sportscar, and I remain a petrolhead, petrol would be first on my list because of the perky fun of bhp. But my point remains. Until you've tried this V12 Diesel you're really being nothing but blinkered in your choice of what makes a sportscar or supercar.

I suppose this is a close as most of us without an HGV license will get to a driving a Scania tractor unit (without a trailer,obviously). Still, the chance of Audi letting me near an R8 is pretty remote, diesel or otherwise...

The diesel R8 can only be the final confirmation that petrol is more or less dead.

With diesels now offering similar or better performance, better in-gear acceleration, more refinement, better economy and better emissions than their petrol equivalents, i'm finding it very hard to find a reason to suggest a petrol version over a diesel, except perhaps the soundtrack, only slightly sharper handling and if you like changing gears. Hardly good enough reasons though against the more compelling diesel facts, and that's coming from me who has always been a petrol fan.

Who'd now bet against a diesel Porsche Cayenne or Panamera? And i bet we'll see diesel Lambos, Maseratis, BMW Ms, AMGs and the like within the next 5 years. And what about the ultimate sin - a diesel 911 or Ferrari.

Why do people still go on about the noise?-There are plenty of diesels out there that sound great, and not "despite" being diesels but BECAUSE they are diesels (BM's twin turbo for instance, volvo's 5 cyl, Fiat/Alfa/Lancia 5 cyl). And there are plenty of petrols that sound awful (Ford CVH, anything with a way oversized exhaust). Even VW's 4 cyl TDI can sound good, especially when its comming from a Fabia VRs or Ibiza Cupra driven in anger-theres something quite unexpected and cool about hearing such a beefy noise coming from a small car.

Roy, have to take issue here. Firstly, John Latham deserves credit for his instructive post. Roy, could you explain where 'more refinement' comes from? How does a much higher compression ratio, even with the latest piezo-aided multiple injections per cycle, provide more refinement? Likewise 'better emissions'? As John Latham says carbon dioxide emitted per kilometre maybe less but carcinogenic filthy particulate(soot) certainly isn't, nor Nitrogen oxides(NOx). On soot reasons alone diesel passenger vehicles have been effectively banned from Japan and California until now. NOx emissions from diesels are at least three times higher per km than petrol(Euro3/4). Only with expensive, complex, weight-adding particulate traps and NOx catalysts(urea) can the likes of Mercedes with 'BLUETEC' start to offer modern common rail diesel engines alongside their latest indirect and increasingly direct injection petrol engine range in America, complying with the equivalent of Euro6(LEV II) regs., that's PM, particulate matter, one-fifth and NOx one-third of current best(Euro4).